Bell’s Palsy is characterized by the sudden onset of temporary paralysis or weakness of the muscles on one side of the face. This occurs due to inflammation or damage to the facial nerve (Cranial Nerve VII), which controls most facial expressions. While cosmetic changes are visible, the inability to control the muscles around the eye is often the most serious health concern. Loss of eyelid function leaves the eye highly exposed and vulnerable to severe damage if protective measures are not implemented immediately.
How Bell’s Palsy Affects Eyelid Function
The facial nerve innervates the orbicularis oculi muscle, the circular muscle that closes the eyelid. When Bell’s Palsy compromises this nerve, the signal is disrupted, causing an inability to fully blink or shut the eye on the affected side. This mechanical failure to close the eyelid completely is medically termed lagophthalmos. Since the muscle responsible for opening the upper eyelid is controlled by a different cranial nerve, the eye remains partially or fully open even when closure is attempted.
This paralysis also impairs the automatic, involuntary blinking reflex that distributes the tear film across the ocular surface. The lower eyelid may also droop outward, a condition called paralytic ectropion, which further exposes the eye. This combination of incomplete closure and absent blinking prevents the eye from receiving necessary moisture and protection. The result is a fragile ocular surface constantly exposed to air, dust, and other irritants.
Specific Eye Conditions Resulting from Facial Paralysis
The constant exposure resulting from lagophthalmos quickly leads to Dry Eye Syndrome. Without regular blinking, the tear film evaporates rapidly, leaving the front surface of the eye dehydrated. This dryness is compounded because the facial nerve can also affect the glands that produce the watery and oily parts of the tears, potentially reducing tear film quality. Patients often report a stinging or burning sensation, redness, and a feeling that something is stuck in the eye.
A more serious consequence is the development of Exposure Keratitis, which is inflammation and damage to the cornea. Prolonged exposure and dehydration cause corneal cells to break down, ranging from minor abrasions to significant epithelial defects. If this damage is left untreated or becomes severe, it can progress to a Corneal Ulceration. This is a medical emergency that carries a high risk of permanent vision loss or scarring. The loss of sensation that sometimes accompanies facial nerve issues can mask the severity of this damage, meaning the patient may not feel the pain of a worsening ulcer.
Paradoxically, many people with Bell’s Palsy experience Epiphora, or excessive tearing that runs down the cheek. This is usually due to a failure of the tear drainage system, not an overproduction of tears. The paralyzed orbicularis oculi muscle is responsible for pumping tears into the nasolacrimal duct system. When this pump mechanism fails, tears accumulate and spill over the lower eyelid, which is often compromised by paralytic ectropion.
Essential Strategies for Ocular Protection
Immediate and consistent intervention is necessary to prevent serious complications from corneal exposure. The primary strategy involves rigorous ocular lubrication to supplement compromised natural tear function. During the day, patients must frequently use preservative-free artificial tears, often every two hours, to keep the eye hydrated. It is also helpful to gently assist the eyelid in closing with a clean finger periodically to manually spread the tears and maintain moisture.
For nighttime protection, thicker lubricating ointments or gels are applied before sleep, providing a longer-lasting moisture barrier than liquid drops. Since the eye is often open during sleep, which exacerbates drying, a physical barrier is also required. This can involve taping the affected eyelid shut with soft medical tape after applying the ointment. Alternatively, wearing a moisture chamber or an eye patch helps prevent dust and air from reaching the surface.
It is important to wear glasses, sunglasses, or goggles during the day, especially outdoors, to shield the eye from wind, dust, and bright sunlight. Due to the high risk of corneal damage, any patient diagnosed with Bell’s Palsy should be immediately referred to an ophthalmologist or eye care specialist for monitoring.
Surgical Interventions
In cases where recovery is prolonged or corneal damage is severe, surgical interventions may be needed to protect the eye. Procedures such as tarsorrhaphy, which temporarily sutures the eyelids partially closed, or the implantation of a gold weight into the upper eyelid to assist with closure, can be performed to ensure the cornea remains safe.